This
project is realised in collaboration with John
Eekels, Holland. John was asking for a substitute for the
no longer available SEAS
W11CY001 and after some search we decided
to give the new SEAS W12CY003 a try. This driver features
a classic paper cone with standard coating on the rear
and Nextel coating on the front, giving it a nice
appearance as can be seen below. I have previously done a
two-way from SEAS CA18RLY+22TAF/G (not published) from
which I've had some good times, thus the SEAS 22TAF/G
tweeter was the one I wanted to try out in this
construction. To my ears the 22TAF/G is doing as well as
the HIQUPHON OWI, that's how high I rate it. The small 19
mm alu dome combined with a wide fabric surround seems to
combine the best from 3/4" and 1" domes. It may
not have the power handling of a well designed 1"
dome, but less can sometimes do.
So, John shipped his cabs
+ W12s to Denmark and this really makes life easy for
me.....except that I can't keep the speakers once
finished. Well, we can't have it all, can we?
WAFTEN was a possible
name for these speakers, but eventually we decided on
Eekels. But WAF-10 is certainly what they are. It doesn't
get much better on this important parametre.
The Cabinet
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Eekels' cabs are made
from 17 mm plywood (incl. veneer). America cherry
for the sides and rear, fillets made from African
bubinga and front panel from solid curly maple.
The dimension leaves an internal volume of 4.8
litres and I suggest a vent tuning of 60 Hz
requiring a 35 (ID) x 100 mm vent. Right out of
the box the W12 had an Fs of 80 Hz but after some
heavy massage ended at ~65 Hz; not unusual for a
4" driver.
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The Drivers
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Midbass:
SEAS W12CY003
(E0044) - - - Tweeter: SEAS 22TAF/G
(GH1283)
The Complete W12 Kit. Cored coils for
notch filter replaced by air-cored, 1.75 ohm.
The X-over
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The Kit
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Complete kit
available from Jantzen Audio: contact@jantzen-audio.com
Pay notice to L2031. The combined
resistance of coil and resistor should be 4.8-5.2
ohm. Pay also notice to the size of components
for this construction. There's not an awful lot
of space available for the crossover. I suggest
splitting the crossover in two, e.g. bass section
on rear panel and tweeter section on top.
An
immediate up-grade would be replacing C1021 and C1041 with
Superior-Z caps. Consider space when doing so.
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Suggested crossover
layout for the Eekels. Bass section on rear
panel. Before you mount the front panel and vent,
try taking a look at your crossover layout. I've
split the low-pass and high-pass section to get
the coils as far away from each other as
possible. The bass section is some 80 x 130 mm
and should be able to pass through the bass
driver hole, but check it out before you start
poring glue. There are two holes in the bass
section for the terminals, so don't drill the
holes for the terminals before you have the
crossover in place. The tweeter section may be
placed on top panel above the vent, so do not
drill the vent hole before you have the tweeter
section in place. By using the suggested
components everything should fit into the tiny
cab and not take up too much space. I've been
using Superior Z-Caps for testing and this would
take another 4 litre box alone for the crossover!
But I like an integrated solution and suggest
Cross Caps for this application.
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Measurements
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Let's start taking a look
at the response graphs from the SEAS data file.
Looks really good, doesn't it? Plus/minus 1.5 dB
from 500-4000 Hz. Not bad at all. Now, the file
doesn't tell the size of the baffle, only the
volume of the cab behind the driver = 2.5 litres.
So, great expectations.....
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Red = response on my
"infinite" baffle, 60 x 100 cm, wide
enough to show what's going on around 800-2000
Hz, the trouble area, where surround resonances
usually occur. Well, a 5 dB peak at ~900 Hz was
rather unexpected, but playing the W12 fullrange
sounded very good indeed and didn't suggest any
problems. Mounting any small driver on a tiny
baffle is calling for trouble, so I was prepared
for having to equalise the upper midrange. Blue
and green = the two W12 drivers in the Eekels
cabs.
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Left: Green and purple =
response from drivers driven from crossover. Blue
= summed response from final crossover. Red =
summed response without mid notch filter.
Right: Response of drivers in cabinet without
crossover.
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Left: Response from final
construction @ 1 metre/2.8V. Sensitivity of
speaker = 83 dB.
Right: Response of left and right speaker.
Three crossovers were simulated and all tested
with points of crossover at approx. 2.6 kHz, 2.8
kHz and 3.4 kHz. With a point of crossover at 3.4
kHz, the dip at 4 kHz could almost be eliminated
but the two other crossovers were better on e.g.
female vocals and saxophones, so 2.8 kHz was my
final choice.
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Left: Yellow =
tweeter/green with inverted tweeter polarity
displaying the usual suck-out. Reading here taken
between bas and tweeter at 1 meter distance.
Right: Impedance of final system (before
adjusting vent diameter). Due to the notch filter
we have a minimum here at 4 ohms. Now,
mini-monitors at 82-83 dB sensitivity are not
meant for 5 watts single ended valve amps - and
this is no exception.
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The Sound
I'm happy to say this is
a worthy replacement of the old W11XT speaker. This
4" Nextel driver seems to think it's a 5"
driver. Bass lines are easy to follow and I'm surprised
how well it handles vocals. Maybe I should try to compare
distortion from the W11CY001 and the W12CY003. I think
the W12 is simply better.
The 22TAF/G is in line
with my other favourite tweeter, the Vifa XT25TG. These
tweeters never cause me trouble. They just play treble
and they never say: Hey, I'm here! Hear how great I am! A
clear sign that something is wrong.
As always, good minis can do things large speakers
sometimes cannot. The level of transparency from having
the sound radiated from a very small area is special and
playing the W12s in my 12 m^2 workshop even made me ask
the hypothetical question on whether I could live with only
these speakers....Obviously I cannot, but used in small
rooms, used for the kitchen news radio or for the
computer or workshop, it's an overkill solution to good
sound on limited space.
Moving the speakers to our living
room changed the sound a lot. Driven by my 20
wpc single ended amps the bass level decreased somewhat
and the 83 dB sensitivity was not the favourite disc of
these mono amps. So, in came my Rotel RB981 150 wpc amp
and things changed a lot. If you want to use valves, go
for some minimum 35 wpc push-pull design that can handle
the low sensitivity. You won't play these speakers to
ear-splitting levels anyway, because 50 cm^2 membrane
area simply cannot move a lot of air. But again, the bass
these speakers can play is really good, even to
the point where you can get a certain feel of
the bass; that is if your amp can hold the bass driver
membranes in a firm grip.
I've shown a few people
the draft file during construction and as often is the
case, expectations are too high. Yes, you can add a sub
at 100 Hz and make good sound, but they will never sound
like big speakers, because they still have to
handle the 100-300 Hz region where so much energy is
localised. And don't use them with an electronic
crossover at e.g. 300 Hz. You'll still not have a system
sensitivity above 83 dB, where a true 3-way from W12s and
suitable 6-8 inch bass drivers would easily make 88-89
dB/2.8V. So, be clear on what 4" drivers can do and
what they cannot do - and enjoy the music.
 
Aftermath
John
Eekels comments to the final W12s
Hi Troels,
Another mail from me with some comments on the W12s.
Finally I have finished the W12s. I had some trouble
mouting the X-overs as the terminals on the rear didn't
match the X-over free room….They where just on the
back of the coil, so I couldn't drill on that place. I
have covered the X-overs with 2-component resin, used for
transformers in the tube industrie.
So…..Today Diana Krall visits me; she was standing
just in front of me, right between the W12’s. I
could look her just in her throat, I was falling of my
chair….these tiny speakers are just fabulous!
I’m overwhelmed of the imaging these tinys deliver
me, an unbelievable bass in accordance to the size and an
amazing treble. Specially woman voices, as Diana Krall,
Tracy Chapman etc. are great to listen to on these W12s.
I’ve been driving them by my new KT88 PP tube amp,
and I must say this combination is superb. They need a
steady amp, the KT88 is one, and holds the small woofers
in a firm grip. So as you can see, I’m very pleased
with them, and I will thank you for delivering this big
affort on this project. Attached some fresh pictures,
which I just shot in my attick, approximately 6x4 metres,
but with triangle wall of coarse. So no big volume room,
thus they seem to like my room, and I like them. Thanks
again Troels, I will stay tuned on you’re projects.
Best Regards, John Eekels
 
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